A microclimatic analysis in a typical urban configuration, has been carried out. Using a CFD method, a N-S oriented urban street canyon, with a given H/W ratio, has been examined. The standard k-epsilon turbulence model has been used to simulate a three-dimensional flow field and to calculate the thermo-fluid dynamics parameters that characterize the street canyon. The aim of this study is to investigate the effect of solar radiation on the flow field and thermal parameters within the canyon. A comparison between transient and stationary simulations has been performed to evaluate the importance of considering the thermal inertia effects in an urban street canyon study. The dynamic characteristics of the 3D flow in the canyon have been compared with other numerical simulations and experimental results. Furthermore a thermo-fluid dynamic analysis of natural convection effects on the heat transfer coefficient and turbulent kinetic energy, has been carried out. (C) 2013 Elsevier Ltd. All rights reserved.